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        <title>Document</title>
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        <script>
            // 数据代理：通过一个对象代理对另一个对象中属性的操作（读、写）
            let obj = {x:100};
            let obj2 = {y:300};
            // obj2可以修改obj里面的x
            Object.defineProperty(obj2,'x',{
                get(){
                    return obj.x;
                },
                set(value){
                    obj.x = value;
                }

            })
        </script>
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